The present invention relates generally, as indicated, to multiple conductor electrical connectors and, more particularly, to such a connector that may be used in conjunction with a multiconductor cable to form a cable termination assembly having an internal grounding bus and improved molded strain relief.
The use of multiconductor electrical cables in the electronics industry is, of course, widespread. One such multiconductor cable includes a plurality of individual wires, each including a conductor covered by its own insulation, bundled together mechanically, e.g. by a fasterner, an external sheath, or the like. Another such cable includes a plurality of electrical conductors contained in and electrically isolated from each other by a unitary body of electrical insulation. Flat or ribbon cable is a particular version of this latter multiconductor electrical cable type, as is well known. The insulation ribbon cable may be of various electrically non-conductive materials, such as plastic or plastic-like materials, polytetrafluoroethylene (e.g. Teflon), fiberglass, or like materials. Flat ribbon cables may have multiple conductors therein numbering more than eighty.
In some uses, such as for high speed signal transmission, of ribbon cable, it has been found desirable to provide an electrical ground potential or other reference electrical potential (hereinafter ground isolation) between signal carrying conductors by connecting alternate conductors (hereinafter ground conductors) of such a flat cable to a ground reference potential, for example. Moreover, for high speed signal transmission purposes woven ribbon cable and cables having Teflon or like insulation have been found most desirable.
Various techniques have been employed to terminate multiconductor cables, for example, by connection of the conductors thereof to respective electrical contacts that may be grouped in a male or female socket-like electrical connector device (hereinafter cable termination) to facilitate electrical connection of such conductors to other circuits, such as those terminating at terminal sockets of a computer module or the like. Such a cable termination assembled to a multiconductor cable is referred to as a cable termination assembly. In one such technique the ribbon cable, a plurality of electrical contacts, and several non-conductive body parts are placed in a jig press and using the latter are secured together mechanically to form a cable termination assembly. Another technique for terminating multiconductor cables disclosed in commonly assigned U.S. patent application Ser. No. 656,303, filed Feb. 2, 1976, now U.S. Pat. No. 4,030,799, issued June 2, 1977, provides for direct penetration of electrical contacts through the cable insulation to connect with respective conductors therein and a body of dielectric material molded directly about at least part of the contacts and cable to secure the same as an integral structure.
In the past, to obtain ground isolation for such multiconductor ribbon cables the ground conductors were connected to respective contacts of the cable termination assembly and each of these contacts were in turn connected to an external ground. Therefore, usually less than half of the remaining contacts of the cable termination assembly, i.e. those coupled to the respective signal carrying conductors, were actually available to carry useful signals.
Strain relief, i.e. a mechanism that prevents force applied to the cable termination assembly tending to separate the termination from the cable from detrimentally affecting the integrity of the connections between respective conductors and contacts, is provided in the above mechanically assembled cable termination assembly by applying a mechanical binding force to the cable to secure it between several body parts. In the molded cable termination assembly strain relief is provided by the intimately engaged insulation and molded body therearound also preferably with a chemical bond being obtained between the insulation and the molded body. Moreover, in commonly asigned copending U.S. patent application Ser. No. 752,469, filed Dec. 20, 1976, there is disclosed a lip seal insert for securing an electrical cable having insulation of a material, for example, of Teflon, that ordinarily will not readily bond with the molded body in the latter to provide the strain relief function.